MO Department of Health Drinking Water Well Survey

The following is a bit of information from the 1994 private drinking water well survey done by the Mo Department of Health. Unfortunately, this is the latest data set available. You can pick up this report from your county health department office. These are the highlights.

People drinking water from any type of well that has tested positive for coliform, reported illness at more than two times the rate of persons drinking from coliform negative wells (near 6% versus 2%).

Of the 861 wells tested statewide, 56% were contaminated with coliform bacteria and 22% with Escherichia coli (E. coli), human waste indicator bacteria. (Frank’s note: MoDNR tried to use this measurement to indicate the other 34% were contaminated by livestock wastes. Unfortunately for MoDNR, few of those 34% sites were where there had been livestock near the well, as backed up by DoH field notes.)

For most of the wells that had detectable nitrate, nitrate levels were not of public health significance. Atrazine detects were all below action levels.

Northwest Missouri had the highest contamination results (80.5% positive for coliform bacteria, 50% positive for E. coli bacteria.)

In state wide samples (everywhere in the state), three well characteristics were found to be statistically significant. The younger wells, the deeper wells, and those with plastic or metal casings were less likely to be contaminated with bacteria.

Survey Definitions

Coliform bacteria: Special group of bacteria commonly found in the intestinal tract of warm-blooded animals. Because of this association, coliform serve as an indicator of fecal contamination. Micro-organisms in fecal wastes can cause illness with symptoms of nausea, vomiting, abdominal cramps, diarrhea, or fever.      TC - Total Coliform Bacteria detects
                 EC - E. coli Bacteria detects

Nitrate: One chemical form of nitrogen. Nitrogen is essential for making protein in our bodies. Bacteria in the digestive tract of young children can convert nitrate to nitrite, which can be absorbed into the blood and interferes with moving oxygen from the lungs to body tissues. Signs of nitrate/nitrite poisoning include fatigue, lack of stamina and in severe cases, blue color of the finger tips, toes and lips.

Atrazine: A herbicide used for weed control on cropland, primarily corn and milo. It is the most common agri-chemical used in the U.S. Health concern about atrazine centers on its cancer-causing potential. Increased cancer risk would require life-long exposure to contaminated water or occupational exposure to atrazine concentrate.

Sample Results by Region

Area 1 - the Ozarks/limestone hill area of south MO, except for Area 6 and the Special Area
Area 2 - West Central MO
Area 3 - Northwest & North Central MO
Area 4 - Northeast MO
Area 5 - the Bootheel
Area 6 - the St. Francis Mountains
Special Area - the Scenic Rivers and Ozark Foot Hills
TC - Total Coliform Bacteria detects
EC - E. coli Bacteria detects

Sample Results by Well Type

Drilled wells is the primary type (92%) in the Ozarks (areas 1, 6 & special areas).

Dug or bored wells is the primary type (65%) in the northwest (area 3).

Sand point wells is the primary type (85%) in the bootheel (area 5).

		Frank Wideman widemanf@missouri.edu 321 North Main Street Perryville, MO  63775 (573) 547-4504 Last updated January 18, 2006
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